/Engine/Plugins/Enterprise/DatasmithImporter/Source/DatasmithImporter/Public/DatasmithImportContext.h
Use a cache of known labels and a LUT of indices to speedup that step. ReplacesFActorLabelUtilities::SetActorLabelUnique.
class FDatasmithActorUniqueLabelProvider : public [FDatasmithUniqueNameProvider](API\Runtime\DatasmithCore\FDatasmithUniqueNameProvider)